rexone

Hello Dennis, how you doing

bcarpman

Yeah, I was thinking more about that after I wrote it. I guess it really just depends on the amount made. I know about what it costs to make custom SS single wall headers, and know how cheaply they can actually be produced if you're getting them made in reasonable sized batches, but I guess I really don't have any clue how many sets of headers CMI makes or MR buys. Is it 10 a year or 500? If they're making them in decent sized batched, you can setup the benders and crank them out pretty quickly. Of course welding up the double walls has to be interesting. All the more reason for others to step up and make KE style cast aluminum headers.

Rage

I had occasion to talk to a race program individual that stated some years back they tested every header package that they could get their hands on and found that the CMI's produced the best hp. They also tried the KE cast manifold which worked well producing hp but experienced "cracking" of the internal cast runners and hydrauliced a motor as a result. Since reliability was a top priority they dropped future consideration of the KE manifold.

cougarman

Interesting, I heard some other reasons ??
Guess what they use it over Sea's in there racing circuit.

Cougarman

James

The cast aluminum manifolds are no more likely to melt than aluminum heads or aluminum pistons, assuming they have proper cooling. Stopping water flow to either the SS or cast manifolds under high load conditions can result in failure.

For the people who swear by the stainless exhaust and say they never leak probably have never had them off and pressure tested them with 30 psi to prove weather they leak or not. And for those who have hydroed and engine - well those guys already know they leak.

I know from experience that a quality SS manifold is relatively low risk item, however my personal experience is that aluminum is less likely to fail all things being equal.

bob

Rage, interesting comment as I had good inside info that Merc had made offers to KE to purchase his pipes. KE opted not to go there. I have over 400 hours on a pair and I have run at least 750 hp into them and for the last 200 hours over 900. Not a single issue. However, I do keep them supplied with water to keep them properly cooled.

Rage

All I can say is this what I was told was from a reliable source. Maybe just bad luck or like you say cooling problems. Sounds like others are racing the KE with success and reliability. Of course I have also seen similar conflicting comments on the CMI's. Some say they have never had a problem and others say the can not keep them on the boat. Seems like more are reporting problems than not. I was personnally planning on purchasing the KE until I discovered that they do not make one for the 496 and have no plans to.

An addenum, I asked KE if they still Extrude Hone the tubes. They do not.

Annother comment on why Mercury is using CMI's is maybe they make the most hp.

Rage

What " other reasons"?

cougarman

Perhaps all I should say is the European Teams love them.


Cougarman

BGIII

If that is the case, then why would they use Edelbrock heads? We all know that they are not the best available.

525-550 horsepower is not rocket science. They are buying what makes the boat look faster/better and what they can get the best deal on. With the outrageous prices Mercury Racing charges for their product, it has to look like it is different or better than regular Mercury product. I don't think a guy that is willing to pay 300-500k for a boat w/ 525's and goes as far as to have airbrushed battery hold downs, wants a big old clunky set of KE's under the hatch. It doesn't matter how much horsepower, how good or how reliable they are. I do know that if I had a set of 525's in a 3 year old boat and needed to buy $10,000 worth of new headers because they were leaking, I would be the most pissed off guy on the internet.